Another common kind of argument is also often described as a slippery- slope argument. In these arguments, the claim is made that, once a certain kind of event occurs, other similar events will also occur, and this will lead eventually to disaster. The most famous (or infamous) argument of this kind was used by the U.S. government to justify its intervention in Vietnam in the 1960s. It was claimed that, if the communists took over Vietnam, they would then take over Cambodia, the rest of Asia, and other continents, until they ruled the whole world. This was called the domino theory, since the fall of one country would make neighboring countries fall as well. Arguments of this kind are sometimes called domino arguments. Such arguments claim that one event, which might not seem bad by itself, would lead to other, more hor- rible events, so such arguments can also be called parades of horrors.
Causal slippery slopes can also slide into good results. After all, someone who wants communists to take over the world might use the above domino ar- gument to show why the United States should not intervene in Vietnam. Such optimistic slippery-slope arguments are, however, much less common than pa- rades of horrors, so we will limit our discussion to the pessimistic versions.